Diaphragm preselector for photographic objectives



ApriIZS, 1961 U Z 2,981,169

DIAPHRAGM PRESELECTOR FOR PHOTOGRAPHIC OBJECTIVES Filed May 8, 1958 jyi.

AGENT- United States Patent DIAPHRAGM PRESELECTOR FOR PHOTO- GRAPHICOBJECTIVES Karl Heinz Schiitz, Kreuznach, Rhineland, Germany, assignorto Jos. Schneider & Co., Optische Werke, Kreuznach, Rhineland, Germany,a corporation of Germany Diaphragms of this-type having one of theiriris leaves extended to form an operating lever are already known,

'e.g., from U.S. Patent No. 2,803,182 issued August 20,

1957, to Franz Werner.

The principal object of my present invention is to provide a system ofthis general character which is of more compact construction than thosepreviously devised. A more particular object of this invention is toprovide a system of this type, having means for preselecting a desireddiaphragm opening with the aid of a special iris leaf, in which suchleaf serves only as an adjustment-limiting means and not as a link inthe transmission of force from an actuating member to the usualdiaphragm-setting ring, this arrangement thus enabling the iris leavesto be of more delicate construction than would be the case if one ofthem were to act as a torque-transmitting lever.

A feature of my invention resides in the provision of a contoured diskor cam co-operating with a projection on one of the iris leaves, incombination with mechanism for imparting limited rotation under thecontrol of an actuating member to the diaphragm-setting ring which hasthe usual oblique grooves wherein the extremities of the iris leaves areslidingly guided. In a preferred embodiment the actuating member iscontrolled, in a manner known per se, by the shutter-release button. ofthe camera and acts upon the diaphragm-setting ring through theintermediary of a bell-crank lever or equivalent means for translatingits own motion into rotation of the ring.

The invention will be described in greater detail with reference to theaccompanying drawing in which:

Fig. 1 is a side-elevational view, partly in section, of an objectivehousing carrying a diaphragm preselector according to the invention;

Fig. 2 is a cross-sectional view taken on the line HH of Fig. 1;

Fig. 3 is a fragmentary view similar to Fig. 1, showing certain parts ina difierent position; and

Fig. 4 is a view similar to Fig. 2, showing certain parts in a positioncorresponding to that of Fig. 3.

The objective shown in the drawing comprises a cylindrical diaphragmhousing 1 in which the iris leaves 2 are pivotally mounted by means ofpins 2a. Each leat is also provided with a pin 2b which is slidablyguided in a groove 3- of a setting ring 3 as is well known per se.Rotation of the setting ring from the position of Fig. 2 into that ofFig. 4 moves the iris leaves 2 from wide-open to nearly closed diaphragmposition.

In accordance with this invention I provide an extremity 4 of one of theiris leaves with a stud 4a projecting towardan annular cam disk 5, thelatter having an inner flange with a contoured-periphery 5a forming anabutment for the stud 4a; this periphery has also been indi- PatentedApr. 25, 1961 cated in dot-dash lines in Figs. 2 and 4. Disk 5 isrigidly coupled, through a pin 6a, with a diaphragm-control ring 6 whichsurrounds the housing land bears the usual aperture scale (not shown).

A cylindrical rearward extension 7 of housing 1 is provided withsuitable means, such as a bayonet coupling, for attaching the objectiveto the body of a camera schematically indicated at 16. Cylinder 7surrounds the rear portion of housing 1 and mounts a bracket 8b withinwhich a rod 8 is lodged for displacement parallel to the optical axis ofthe system. Rod 8 is controlled by a lever 9, pivoted at 911, which canbe swung clockwise (as seen in Fig. 3) by the tripping of theshutter-release button 10 of the camera 16. The rod 8 carries a pin 8awhich is straddled by the bifurcate end of a bell-crank lever 11 havingas its fulcrum a screw 11b projecting from bracket 8b; the other end ofthis bell-crank lever carries a stud 11a against which a lug 12',secured to setting ring 3 by screws 12a, is normally urged through aspring 13.

In operation, the control ring 6 is first adjusted to an angularposition corresponding to a desired diaphragm opening. Ring 6 entrainsthe cam disk 5 without, however, affecting the setting of the irisleaves 2 since the stud 4a is held spaced from the contoured shoulder 5aby the spring 13 urging the setting ring 3 counterclockwise as viewed inFigs. 2 and 4. This causes the bellcrank lever 11 to occupy the positionshown in Fig. 1 in which rod 8 projects rearwardly beyond coupling 7 toits maximum extent, the iris diaphragm 2 being then in its wide-openposition shown in Fig. 2. When the trip button 10 is pressed, lever 9oscillates about its fulcrum 9a to press the rod 8 forwardly, as shownin Fig. 3, thereby swinging the lever 11 counterclockwise and displacinglug 12 as well as setting ring 3 against the force of spring 13. Thismovement is arrested when the stud 4a on iris-leaf extremity 4 abuts theshoulder 5a of cam disk 5 so that the iris leaves, interconnected by thering 3, come to rest in a position corresponding to the preselecteddiaphragm opening.

When the button 10 is released, the parts are restored to the positionof Fig. l by the spring 13 and the diaphragm 2 returns to its wide-openposition.

My invention is, of course, not limited to the specific arrangementdescribed and illustrated but may be embodied in numerous modificationswithout departing from the spirit and scope of the appended claims.

I claim:

1. In a photographic objective, in combination, a housing, a controlring rotatably positioned on said housing, a rotatable cam disk in saidhousing coupled with said control ring for entrainment thereby, asetting ring coaxial with said cam disk and rotatably positioned in saidhousing, an iris diaphragm in said housing comprising a plurality ofleaves pivotally connected with said housing and in positive engagementwith said setting ring for movement between different positionscorresponding to various diaphragm apertures, a projection on one ofsaid leaves, said cam disk having a contoured periphery adjacent saidprojection, spring means connected with said setting ring and with saidhousing for rotating said setting ring in a sense urging said projectionaway from said periphery and tending to maintain said leaves in anextreme position corresponding to maximum diaphragm opening, andoperating means on said housing for rotating said setting ring againstthe force of said spring means until said projection engagessaidperiphery, thereby limiting the extent of diaphragm-closing movementof said leaves, said operating means comprising a bellcrank leverswing-able in a plane substantially parallel to the axis of rotation ofsaid setting ring and an actuating element displaceable in a directionsubstantially parallel to said axis, said lever having a shorter armengaged by said actuating element and a longer arm engaging said settingring whereby a relatively small axial displacement of said elementcauses a relatively large angular displacement of said setting ring.

2. The combination according to claim 1 wherein said cam disk is ofannular configuration and provided along its inner edge with an axiallyprojecting flange having said contoured periphery as its outer surface.

References Cited in the file of this patent UNITED STATES PATENTS GreatBritain Jan. 9, 1957

